Since the beginning of spoken language understanding research in the 1970s, people have dreamed of communicating with all kinds of devices and appliances using speech recognition. Of the many types of interaction that speech recognition affords, command and control (C&C) is perhaps the simplest, both in terms of the interaction model and the required technology. With regard to the interaction model, C&C allows users to interact with a system by simply speaking commands or asking questions restricted to a fixed grammar containing pre-defined phrases.
While C&C interaction has been commonplace in telephony and accessibility systems for many years, only recently have mobile devices had the memory and processing capacity to support not only speech recognition, but a whole range of multimedia functionalities that could be controlled by speech. Indeed, C&C speech products for voice dialing and controlling media have successfully reached the consumer market.